This invention relates to a method of synchronously time-division-multiplexing transducer signals from a multi-element distributed sensor array. If further pertains to a time division multiplexing technique using a digitally encoding portion of a data acquisition system through a three-wire cable. It more particularly pertains to a multiplexing technique that consumes very little power and is very compact, making it well suited for use in miniature, low power, high performance sensor systems such as tactical, surveillance and research hydrophone arrays and accelerometer arrays used for structural vibration analysis.
Two common multiplexing architectures used in data acquisition systems to accommodate sensor arrays are in widespread use, a first, and more simple, architecture is commonly used in general purpose computerized data acquisition systems. This architecture has one centrally located multiplexer circuit embedded within the data acquisition hardware which all of the sensor signals are directly routed to by two wire cables. The advantages of this technique are that it is simple to implement and maintain, and is low power at the sensor sites. A major disadvantage of this technique is that for many element sensor arrays (having greater than 10-20 sensor elements) the cable size becomes large, which will tend to corrupt the parameter being measured when operating in a dynamic medium.
The second architecture, normally used in complex systems such as in aircraft and ships, multiplexes digitally encoded sensor signals onto a two-wire digital data bus. A typical example of a two-wire digital data bus is commonly designated the MIL-STD-1553B and has generally been used as a data bus structure that supports a time division multiplexing technique. Each sensor site has an analog-to-digital converter which encodes the sensor signals, and a transceiver circuit which receives command words from, and transmits sensor data to, a system bus controller. The major advantages of the technique of the second architecture are that all multiplexing occurs over a small diameter, high noise immune, two-wire digital data bus, and that it can accommodate large quantities of sensors. The disadvantages of this technique are that it is complex, costly to develop and implement, and each sensor site consumes a moderate amount of power. In addition, the second technique does not lend itself to very compact sensor packaging.
Thus, a continuing need exists in the state of the art for a method of synchronously time-division-multiplexing transducer signals from a multi-element distributed sensor array to the digitally encoding portion of a data acquisition system through a three-wire cable that consumes very little power and is very compact, making it well suited for the use in miniature, low power, high performance, sensor systems.